日本語道場 — Nihongo Dojo

～ずにはいられない

~zu ni wa irarenai

can't help but

When to use it

Use this to express an emotional reaction or judgment that the speaker cannot suppress — indignation, admiration, doubt, sympathy. It is the stiffer, written-register twin of ～ないではいられない, and shows up in editorials, reports, and formal correspondence where the writer wants to voice a strong reaction while keeping a composed tone. Because it foregrounds the speaker's own feelings, it is unsuitable for neutral factual reporting.

Formation

Verbs: V-ない form minus ない + ずにはいられない → 疑う → 疑わずにはいられない、認める → 認めずにはいられない
する verbs: irregular → せずにはいられない (感心する → 感心せずにはいられない). Never ×しずには.
来る → 来（こ）ずにはいられない (rare in practice).
i-adjectives / na-adjectives / nouns: no direct attachment. Route the feeling through a verb instead: 不安を感じずにはいられない、疑問に思わずにはいられない.
Politeness is carried by the final verb: ～ずにはいられません / ～ずにはいられませんでした.
Subject is normally the speaker (or a generalized "one"); avoid it for third parties' feelings.

Examples

Looking at these figures, I can't help doubting the premise.
I can't refrain from saying a word about the client's handling of this.
I can't help but admire the turnaround in such a short time.
Faced with the delayed delivery, I couldn't help demanding an explanation.
On these terms, I can't help feeling uneasy about profitability.